1. Field of the Invention
The present invention relates to a pre-warning method and a vehicle radar system, and more particularly, to a pre-warning method and a vehicle radar system capable of exchanging roadway information or environment condition between vehicles via vehicle to vehicle communication or vehicle to roadside system communication, so as to aid or improve vehicle pre-warning systems and to enhance pre-warning accuracy.
2. Description of the Prior Art
As traffic safety is more important, vehicle safety equipment is getting more various. In addition to active or passive safety systems (such as anti-lock braking system, electronic brake-force distribution system, traction control system, electronic stability system, supplementary restraint system, etc.), pre-warning protection systems attract more attention. The pre-warning protection system uses an image self-recognition method of machine vision to detect possible situation which may cause danger, and sends out a warning light signal or an alarm sound to a driver in advance. The driver may change a driving direction according to the alarm signals, to avoid a traffic accident due to the driver's careless or blind side of vision.
A common pre-warning protection system, such as a blind spot detection system, an automatic braking system, a forward/rear collision warning system, a lane departure warning system, utilizes a frequency-modulated continuous waveform (FMCW) radar system in microwave form to perform target detections. These detections are performed by radar systems to detect outside environment of the vehicle or moving conditions of targets, so as to inform the driver adequately. However, the accuracies of the radar systems are affected by radar angles or efficiencies; in addition, since the outside environment and surrounding traffic condition are changing as the vehicle drives, the traditional pre-warning protection systems are easily affected by terrain, ground objects, or traffic conditions, and cause miss detection or false alarm, which causes disturbance of the driver or even dangerous accidents. For example, when a former vehicle and a latter vehicle drive on a single two-way lane and the former vehicle is slower and the latter vehicle is approaching the former vehicle, a forward collision warning system of the latter vehicle may not correctly determine the traffic condition in the front due to blocking of the former vehicle. If there is a fast approaching vehicle in the opposite direction, and the driver of the latter vehicle does not notice and overtakes the former vehicle, an accident may thus happen.
As can be seen from the above, since the vehicle radar systems of the prior art only detect outside environment or targets moving condition, miss detections and false alarms might happen because of outside traffic and environment. Therefore, how to enhance a pre-warning accuracy of the vehicle pre-warning systems is a significant objective in the field.